We cannot determine the period in which salt came to be regarded as a symbol of sanctity or entered into the religious ceremonials of the ancients. We know that in the Levitical Law, promulgated in 1500 B.C., every meat-offering was seasoned with salt, and salt is referred to in the “Verbal Instructions” which were enunciated by the founder of Buddhism, five centuries later. By the time of Pythagoras, about 600 B.C., salt was regarded as the emblem of justice, but who shall say when the Arabs first employed it as a token of friendship, or the Chinese offered their first oblation to Phelo, the salt deity of Celestial worship? We read in Herodotus that caravans brought salt from North Africa, and Schleiden tells us that the priests of Egypt preferred the salt of Hammomen to that evaporated from sea-water; but these references do not help us to fix the date when salt became an article of commerce, or tell us when or where or by whom it was first produced in a manufactured form. It was rock-salt which the Egyptians procured from the salt basin of the Sahara, and rock-salt from the margin of the Red Sea was the variety that is referred to by the compilers of Biblical history. But, although the natural crude product was probably the sole form in which it was known in the Western world by the Ancients, and through the vaunted golden epochs of Babylon, Byzantium, and Greece, the Chinese--who had invented explosives before the Romans had perfected the catapult, and had learnt to navigate by the compass while yet the mariners of the Mediterranean were dependent upon the stars and their wits--had probably been familiar for ages with a salt manufactured by a process, the origin of which they had forgotten, but the practice of which was to remain in operation, almost without revision, for further thousands of years.